1. Field of the Invention:
This invention relates to equipment for handling aircraft cargo containers and more particularly to cargo pallets for use in loading wheeled cargo containers.
2. Brief Description of the Prior Art:
Many models of large commercial aircraft are produced in both passenger-carrying and cargo-carrying versions, which have essentially the same airframe but different interior fixtures and doors. The cargo-carrying versions have no seats but are equipped instead with cargo-handling fixtures and large doors to accept the large containers in which air freight is generally transported. Cargo aircraft are also usually equipped with cargo-handling devices such as passive and power-driven rollers in the floor and fixed and retractable stops to retain the cargo containers in place, as well as a restraining net between the cargo compartment and the flight deck. The conventional aircraft cargo containers are constructed to fit within the fuselage of each particular model of cargo-carrying aircraft and are designed to fill substantially the cross section of the cargo bay of the aircraft in order to accommodate as much cargo as possible. Because of the size and weight of the filled containers they are typically handled with large powered equipment. They are loaded through the doors of the aircraft with suitable lifting equipment and are moved into position within the aircraft by the use of the powered or passive rollers installed in the floor of the cargo bay.
Passenger-carrying models of aircraft are easily converted to cargo service by removing the seats. However, passenger aircraft have small doors, and, accordingly, the cargo must be handled in small containers. Recently, a relatively small cargo container has been designed which is adapted to fit through the small doors of passenger aircraft and to be stowed within the fuselage. Such a container is disclosed in U.S. Pat. No. 4,747,504, the entire specification of which is incorporated herein by reference. The containers disclosed in U.S. Pat. No. 4,747,504 are of such dimensions that they can fit through the doors of passenger aircraft and that each container fills only about half of the cross section of the cargo bay. The containers are provided with a bottom frame on which are mounted caster wheels and alignment flanges which engage guide rails fixed to the floor of the aircraft to keep the containers from moving laterally. In use the containers are rolled through the door, aligned with the guide rails fixed to the aircraft, and pushed into place in the cargo bay. The containers are then held in place and prevented from moving longitudinally by cargo stops fixed to the floor of the aircraft.
In addition to their use in passenger-type aircraft, the containers of U.S. Pat. No. 4,747,504 may be used in conventional cargo aircraft, when it is convenient to do so. In such aircraft, the rails for guiding and restraining the containers may be mounted on pallets fixed to the floor of the aircraft by the conventional pallet-restraining clamps attached to the aircraft structure. However, a pallet with guide rails cannot be placed adjacent the main cargo door, because the side rail would block wheeled containers from being rolled through the door, and the center rail would interfere with the movement needed to align the containers with the guide rails in the cargo bay. Consequently, either the area near the cargo door of such an aircraft has to be left empty of cargo, or the containers stowed there have to be secured by other means. The same problem is encountered in those aircraft which are designed for rapid interconversion between passenger-carrying and cargo-carrying service. Such aircraft may have both a passenger door, located at one end of the cabin, and a cargo door, located partway down the side of the aircraft. When the containers of U.S. Pat. No. 4,747,504 are used in such an aircraft, they may be loaded through either the passenger door or the main cargo door. However, when the main cargo door is used, a conventional pallet with guide rails cannot be used adjacent to the main cargo door, for the same reasons as described above.
Accordingly, a need has continued to exist for apparatus which can be located within the fuselage of a cargo-carrying aircraft adjacent to the door and which permits the wheeled containers to be moved laterally to be aligned with the retaining rails running lengthwise throughout the rest of the fuselage while still providing means for securely anchoring containers within the cargo bay near the door.